1) Field of the Invention
The present disclosure relates to activated halo-containing aralkylsilanes and their preparation. The disclosure also relates to rubber compositions containing such silanes and articles such as tires made therefrom.
2) Description of Related Art
The use of the silica/silane-filler system to reduce the rolling resistance and improve the wet traction of passenger car tires is well known in the art. A reduction of rolling resistance and therefore less fuel consumption are also of strong interest for truck tires. However, the use of silica to replace carbon black filler in natural rubber (NR) containing formulations, such as truck tread compounds, is limited, due to the poor abrasion resistance. At the present time, truck tire treads use highly reinforcing carbon black for maximum reinforcement and excellent resistance to abrasion. The replacement of carbon black by silica in truck applications has been hampered by ineffective coupling of the silica to the polymer chains of natural rubber.
The polysulfurized alkoxysilanes, such as bis(triethoxysilylpropyl)tetrasulfite (TESPT), and blocked mercapto-functional silanes such as 3-octanoylthio-1-propyltriethoxysilane, are currently regarded as the most effective and the most widely used coupling agents in rubber compositions for tires, especially those compositions containing styrene-butadiene rubber or butadiene rubber. However, the reinforcing efficiency and abrasion resistance of vulcanizates filled with silica and coupled with sulfur-containing silanes are insufficient to justify the replacement of carbon black in formulations containing high levels of natural rubber.
The use of non-sulfur, halo-functional silanes is disclosed in co-pending applications, namely U.S. patent application Ser. Nos. 11/703,969 and 11/981,371. These disclosures are focused on the use of activated double bonds to improve the coupling between fillers and polymer, notably natural rubber. The halo-functional silanes were found to improve the reinforcing index, dynamic properties, such as tan δ at 60° C., and abrasion resistance of silica filled rubber compositions containing high levels of natural rubber. Unfortunately, these halo-functional silanes are not readily available because they rely on the hydrosilylation of halomethylstyrene or its derivatives, intermediates that are difficult to manufacture in high yields and at low costs.
It would be desirable to have halo-containing silanes for use in various rubber and other applications, such as adhesives, sealants, coatings, glass fiber sizings, and filler treatments, and the like. What is needed then are halo-silanes that are more readily manufacturable because they do not employ a halomethylstyrene intermediate in their manufacture. The present invention provides a solution to that need.